The Home Office is facing legal action unless it reveals key details of its
so-called Snooper’s Charter.

Theresa May, the Home Secretary, has so far declined to explain a proposed “filtering” system that would allow officials to trawl through the public’s private emails, text messages and other messages sent through the internet.

Conservative MPs have been demanding greater clarity of the Mrs May’s plans since last summer. They fear that such technology represents “a tectonic shift in the relationship between the citizen and the state”.

The Information Commissioner has now ordered the Home Office to publish advice ministers received on the design, cost and risks of the new filtering system by May 11.

Dominic Raab (Rex Features)

Dominic Raab, a Tory MP with an interest in human rights, requested the advice in a Freedom of Information request last summer, but Mrs May’s department has refused to publish the guidance citing “national security” concerns.

Mr Raab said: “This far-reaching scheme could drain the swamp of every email, text message and phone call made by every citizen, a tectonic shift in the relationship between the citizen and the state.

“So, it's astonishing that Home Office bureaucrats are risking contempt of court by trying to cover up the most basic information on how the scheme will operate in practice.”

Under the Government’s plans telecoms and internet service providers would be paid taxpayers’ money to log their customers’ emails, internet use and other correspondence in a way that could be easily searched by pubic officials.

The Government initially claimed that only the police and security services would be able to monitor emails and other correspondence under the proposed Communications Data Bill.

However, The Daily Telegraph last week disclosed that dozens of councils and other public sector bodies also want to harness these powers. Even the Health and Safety Executive and the Charity Commission have applied to do so.

If the Home Office does not comply with the Information Notice issued by the Commissioner last week it will be judged as being in “contempt of court”.

A spokesman for the Home Office said: “This legislation is vital to help catch paedophiles, terrorists and other serious criminals. The proposed request filter will further protect privacy by discarding all data not directly relevant to an investigation.

“The cross-party Joint Committee which scrutinised the Bill looked carefully at the proposals and stated that: ‘The request filter will speed up complex inquiries and will minimise collateral intrusion. There are important benefits.’”